Private equity titan Leon Black and his wife Debra, a Broadway producer, melanoma survivor and leading force behind the Melanoma Research Alliance, are buying 19 E. 70th St., the former Knoedler & Company art gallery, which shuttered following a major art fraud scandal in 2009 that is still under investigation.

However, although Candy obtained city permits to transform the commercially zoned space back into its original single-family mansion status, he then put it back on the market for $55 million.

The Blacks are hammering out details to buy the mansion for around $50 million, sources tell Gimme Shelter exclusively.

The manse, which needs more than $20 million worth of renovations, would be a fitting home for the couple’s extensive art collection, which includes one of four versions of Edvard Munch’s “The Scream.”

The Blacks and the mansion’s unofficial listing brokers, the Corcoran Group’s Louis Buckworth and Maria Pashby, declined to comment.

Mo bunnies, mo problems

Embattled millionaire landlord Steven Croman and his wife Harriet just held a splashy Playboy-themed party in the Hamptons. They are renting a $650,000 a month rental for the month of August on Surfside Drive in Water Mill while their own beach mansion, in Sagaponack, is being built.

They paid $650,000 for the month of August to rent the home while their own beach mansion, in Sagaponack, is being built.

The Cromans are also putting the finishing touches on their mega-mansion at 12 E. 72nd St., which they bought for $5.5 million in 2002.

At the time, the manse had 23-rent stabilized apartments, and over the years, Croman made headlines for kicking the tenants out.

Harriet and Steven Croman.Photo: PatrickMcMullan.com

In the Hamptons, some of Croman’s guests told Gimme Shelter they wondered what the couple is celebrating.

Croman is under investigation by Attorney General Eric Schneiderman for using illegal tactics to harass and intimidate people into vacating their rent regulated homes.

On Aug. 1, State Senators Daniel Squadron and Brad Hoylman, Assembly member Brian Kavanagh, Borough President Gale Brewer and Council members Rosie Mendez and Margaret Chin applauded the AG investigation with a statement that in part said: “Steven Croman’s pattern of tenant harassment must come to an end.”

Trophy’s choice

Serial real estate investor and EMM Group partner Michael Hirtenstein has another trophy apartment coming to market — as a $35,000 a month rental — at Delos Living at 66 E. 11th St.

Hirtenstein sold a parking garage to Delos Living and one of the conditions of the sale was that he would have a unit in the luxury building the developer planned to build.

Now Hirtenstein is putting his sixth-floor unit into the rental pool. The 3,363-square-foot, three-bedroom, 3½-bathroom stunner is being listed with Lauren Muss, of the Corcoran Group, who negotiated the sale of Hirtenstein’s garage to Delos.

The building boasts five full-floor residences that all come with over-the-top “wellness” amenities including vitamin C-infused showers, purified air and water, reflexology flooring and a Circadian lighting system that works with an individual’s sleep patterns.

Bullets over Park Avenue

An extremely wealthy and secretive German who was involved in Cold War-era arms deals named Mortimer von Zitzewitz — based in Thailand in the 1980s and is now in Monaco — has changed brokers and is re-listing his 2,200-square-foot, two-bedroom unit at Trump Park Avenue, 502 Park, for $8.95 million.

It was asking $10 million last month. The stunning marble and mahogany space comes with a $2.6 million gut renovation.

Royal touches include coffered ceilings with 22-karat gold-leaf gilding.